<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div style="margin: 20px auto; width: 1700px;">
        <canvas id="canvasa" width="800" height="560">

        </canvas>
        <canvas id="canvasb" width="800" height="560">

        </canvas>
    </div>
    <div style="clear: both">

    </div>

    <div style="text-align: center; margin-top: 50px; font-size: 20px;">
        <a href="javascript: grayEffect()">Gray effect</a>
        <a href="javascript: blackEffect()">Black effect</a>
        <a href="javascript: reverseEffect()">Reverse effect</a>
        <a href="javascript: blurEffect()">Blur effect</a>
    </div>

    <script src="./filter.js"></script>
</body>
</html>